import launch
import launch_ros
from ament_index_python.packages import get_package_share_directory
import os

def generate_launch_description():
    #获取默认的urdf路径
    urdf_package_path=get_package_share_directory('fishbot_description')
    default_urdf_path=os.path.join(urdf_package_path,'urdf','first_robot.urdf')
    default_rviz_path=os.path.join(urdf_package_path,'config','display_robot_model.rviz')
    #声明一个urdf目录方便修改
    action_declare_arg_mode_path=launch.actions.DeclareLaunchArgument(
        name='model',default_value=str(default_urdf_path),description='加载的模型文件路径'
    )
    #通过文件路径，获取内容，并转换为参数对象，以供传入robot_state_publisher
    subscriptions_command_result=launch.substitutions.Command(['xacro ',launch.substitutions.LaunchConfiguration('model')])
    robot_description_value=launch_ros.parameter_descriptions.ParameterValue(subscriptions_command_result,value_type=str)
    
    action_robot_share_publisher=launch_ros.actions.Node(
        package='robot_state_publisher',
        executable='robot_state_publisher',
        parameters=[{'robot_description':robot_description_value}]
    )

    action_joint_state_publisher=launch_ros.actions.Node(
        package='joint_state_publisher',
        executable='joint_state_publisher'
    )

    action_rviz_node=launch_ros.actions.Node(
        package='rviz2',
        executable='rviz2',
        arguments=['-d',default_rviz_path]
    )
    return launch.LaunchDescription([
        action_declare_arg_mode_path,
        action_robot_share_publisher,
        action_joint_state_publisher,
        action_rviz_node
    ])